Timing circuit for telephone calls



April 12, 1932, G. H. PETERSON 1,853,977.

TIMING CIRCUIT FOR TELEPHONE CALLS Filed Aug. 16, 1928 Jap/w@ sw. 2' 1 w di,

l" Il 77 /oe/-n/te Release i INVENTOR BY @.eM/f's//L ATTORNEY Patented Apr. 12,1932.`

nutren s-rnf'rag` GEORGE kH. IPETERSON, lOF BLOOMFIELD,

PATENT oFF! NEW'JERSEY, AssIGNoR 'ro AMERICAN TELE; Q

PHONE w.AND TELEGRAPH COMPANY, A CORPORATION F NEW YORK i c Tri/LING oIRcUiT ron v'131141111110un cALLs Application led August 16, 1928. Serial No. 299,897.-

This invention'relates to the art of telephony and discloses a novel circuit yarrangement for timing telephone calls. V,The circuit does. not measure the eXact length of the callbut operates signaling means lwhen the call has continued-"for a certain length of f time. yUpon restoration of the circuit to normal, thereafter,it will again operate the signal when a like periody of time has again i0 elapsed. This cycleof operations may' be4 repeated'indenitely while the call continues. The circuit .isv started yin operation bythe manual depression'of a key switch, and is restored to normal and started anew by a 15 second depression of the key switch. The

ycircuit, is controlled over the sleeve of an A operators cord circuit, and will function only while the front cord thereof is connected I to atelephone trunk orlsubscribers circuit.

- o The timing circuit employs a clock operatedy mechanism or` other means for yperiodically completingy an electrical circuit. With al connection completed from the A cord circuit to' a called subscriber, the depression of a start key connects the net of a. steppingswitch inthe `circuit .con-

' trolled by the timing mechanism. yEach time this circuit is completed `by the timing pulses, the arms'of the step-ping switch are ncction is established.l Upon failureto de- `press the start keyat the end of such afcycle,

the timing'signal will remain steadily oper-V ,pated until Athe A cord circuitis disconnect- A ed, at'which time the circuit is restored to normal. yAt any intermediate point in the cycle, the circuit is restoredA to normal upon disconnection of the A cord circuit. o

- The detailed operation lof the circuitwill now be explained with reference to the draw` ythe receiver of subset 22 operating mag-` ers loop 7 The rotated one step.- At the last step the'iswvitchv operate asignal,`

Vcuitis operated,the circuit This procedure ing, which shows, timing circuit' associated with an Ak operators `manual cord circuit, which latter vis shown schematically. Callingv and called subscribers stations are alsoV shown on` the drawing in schematic form.

Referring to the drawing, scribers set 22 isv connected central oiiice. connected over loop 7 to the same central `oftice. The manual A operators cord circuit l2 serves to interconnect the two subscribers loops. Associated with the cord circuit 12 is the timing circuit which constitutes the remainder of the drawing. All 'of the timing equipment is located at the centralL oitice in question. 1

The connection is established between subscribers in the usual fashion by removal of from the switchhook to operate a line rsignal at the centraloiiice, whereupon thevoperator there connects the back cord plug 9 of the AW ycord circuit 12 to the callingsubover loop 6 to a jack 8 ofthe calling subscribers loop. Upon ,ing the front cord plug 18 of cord circuit 12 to jackll associated ywiththe calledsubscrib- Y operator then rings onzsubscribers line 7. p. Associated with the sleeve circuit of the plug 18 is lead 20-Which connects with the timing mechanism. When plug 18 is connected to jack 11, relay 2 ofthe timing cirbeing traced from battery 'through thewinding of relay 2, over lead 20 andk the sleeve circuit of plug 18 to ground through resistance 21 connected to the sleeve of jackll. The operation of relay 2p1epares the timing circuit for operation under controly of the fmanually operated start V'key 13. I l

The GAZ Operator having established the connection as explained above, supervises on the connection until the called party answers.

When the front cord supervisory lamp is extinguished indicating such to be the case, the

to start timing of the call. of key lit-connects ground to Called subscribers set 23 is a wiring diagram of the on a circuitrom battery, through the right winding ot relay 19, through the lower normally closed contacts of switch 5 to ground at key 13. Relay 19, upon operating, immediately locks to ground on a circuit from battery, through resistance 3, left inner front contact and left winding of relay 19, to ground at the front contact. of relay 2 which latter, as was explained above, is operated to ground over the sleeve circuit of the called station.

The operation of relay 19 connects the timing means to the stepping switch and starts the timing of the callas follows. The rec# tangle 15 represents some sort of timing device for periodically connecting ground to lead 24. Any suitable device may be used for this purpose, such as a clock operating a cog which closes switch 25 momentarily at periodic intervals, or a slow operating relay or switching arrangement might used which required an appreciable time between successive operations. In the present case it Will be assumed that the device 15 closes switch Q5 once every 36 seconds. The operation of switch 9.5 controls the operation ot the stepping switch.

The stepping switch is shown at T. Two arcs T1v and TL are required for the switch,

` having associated therewith rotatable arms 26 and Q7, respectively. The arms are mounted on a common shaft which latter is controlled by an operate magnet 16 and a release magnet 17. For each operation of magnet 16, the switch arms are rota-ed one step in a clockwise direction. Upon the iirst operation of magnet 1G, the arms are rotated from the normal position as shown on the drawing to contacts 1 on the stepping switch arcs. For successiif'e operations the arms pass successively over steps 2, 3, etc. up to 10, after which no further rotation occurs. Upon a single operation ot' the release magnet 17. the arms are quickly rot-ated under spring tension in a commer-clockwise direc tion to the non-operated or normal position as shown.

The operation of switch 5 is controlledk by arm E27 oi' the stepping switch. lith the stepping switch in its normal position as shown, insulating segment l aiixed to arm 27 depresses the movable contacts of switch 5 in the manner indicated, causing the closure of the lower contacts. :is soon as arm 2T rotates one step in a clockwise direction, segment 4 moves oil the movable contacts switch and the latter, being under spring tension, immediately move upward ca'A "ing the closure oit the upper contacts. Thus witz: the stepping switch normal, the lcwer or normal Contact of switch is closed and with the arms ot the ,eppi g switch off normal, the upper or oil-normal contacts are closed.

Returning now to the operation of the timing circuit, each time ground is connected to lead 2st, magnet 16 operates advancing the arms of stepping switch T one step. The circuit is traced from bat ery, through the winding o'l magnet 16, left outer front contact of relay 19, over lead 24, through contacts of switch 25 to ground. With 3(5- second intervals between successive steps, a period of about 6 minutes will have elapsed when the arms are rotated to step 10. W'hen the arms make contact with step 10, a circuit is closed to light lamp 1a. rhis circuit is traced from battery, through lamp 14 to conducting segment 29 of arc T2, through arm 27 to ground associated with contact 10 of arc T2. Lamp 14 remains lighted until extinguished by the operator. No further circuit operation will occur until then. The operator, upon noting the lighted lamp will make note of this fact and restore the circuitto normal by again de iressing key 13. r1`he depression of key 13 short cir- The circuits relay 19 causing its release.

cuit for accomplishing this is traced from battery, through resistance 3, left inner front contact of relay 19, contact 10, arm QG, and conducting segment Q8 of arc T, and over lead 30 to ground at key 13. It will be seen that this direct path to ground shunts the left or holding winding of relay 19 causing its release. Resistance 3 is merely a current limiting device in this operation.

The release of relay 19 closes a circuit to operate the release magnet 17 to restore the stepping switch to normal. The circuit is traced from battery through the winding of magnet 17, oil-normal contacts of switch 5, to ground at the right outer back contact of relay 19. During the restoration of the stepping switch to normal, lamp 1% remains lighted over the circuit from battery, through lamp 14, right inner back contact of relay 1.9, to ground at key 13, assuming, of course, that the operator holds the key depressed while the stepping switch being restored.

As soon as the stepping switch returns to normal, relay 19 reoperates over the circuit rom battery, through the right winding of relay 19, normal contacts of switch 5, to ground at key 13 assuming the key still depressed. lVhen relay 19 operates, it again immediately locks through its left winding to ground at relay 2 as explained above. The operation of relay 19 opens at its right inner contacts the circuit described above for maintaining lamp 1a lighted. T he extinguishment of lamp 111 furnishes a signal to the operator that the stepping switch has restored to normal, whereupon she releases key 13. It should be pointed out her-y f course, that key 13 need only be depressed a brief interval of time for the above operations to be accomplished as the stepping switch is restored very quickly.

The reoperation of relay 19 starts anew ico fia

vthe lapse of or i about 12 minutes from- ;ment of the call. VEach time K plug 18 removes thel the cycle of operationst which terminates 4in the lighting of lamp 14'. This will occur-at the commencelamp 14 lights, the cycle of operations may be repeated by depressinglrey 13, provided, of course, plug 18 is left connected to jack 11.

Vlien thesubscribershangup, the lighting of thev supervisory' lamps associated lwith the front and baclrcords of the A cordv circuit'will `apprise the A operator that the call is complete."r The fA 'operatorv will thereupon disconnect *plugs 9 and-18 `from jacks 8 and 11, respectively.v The disconnection of plug 18 will restore the timing cirf' cuit'to normal iffthe stepping switch is in anyV ol'-normal'position at the moment of such disconnection. The disconnection of ground from leady 20', thereby opening the operatingcircuit for re- 'lay 2, causing' its release. The release ofrelay 2 completes a circuit from battery through A.ating magnet 16 and 'the winding of release magnet'l?, off-normalcontacts of switch 5,k which are closed in any ott-normal position, to ground-through the backcontactof relay 2. The'stepping switch is thus restored-to normal. Therelease ofy relay 2 in turn releases relay-19, by opening' at the front contact of relay 2,- the holding lcircuit through the-left winding of relay 19. The releaseof relay 19 disconnects theintermittent grou'ndat 15 fromthe operthus all circuits are restored tonor'm'al.vr Y n n The timing circuit described does Vnot in vgeneral commence timing the call from the moment the start key 13`is depressed.` This is due to the lintermittent grounding oflead 24 through" the clock mechanism. Infthe 'presentpinstance itjwas assumed that a groundis connected to lead 24 once every v3b seconds; 13 happens to be depressed. immediat-ely after lead 24 has beengrounded, Y

If :the ystart key approximately 36 vseconds must elapsefbebor'e this lead will againbe grounded to step the'stepping switch around tothe first step, andl 6 minutes` will'elapse before the arms of the stepping switch -arrive at lstep 10 to operate Vlamp 14. 0n the other hand, if lkey 13 is depressed just before 'lead 21 is grounded, the steppingrswitch will be immediatelyrotated to step-1,1and only 5 minutes and :24 seconds will elapse until the switch arms arrive at steplO to operate'lamp 14. Thus there -is a spread of 86 Vseconds which represents the possible error in timing. Thissprcad may, ofcourse, becut in half by groundinglead 2eonce every 18 seconds and providing 20 contacts onthestepping switch instead of 10. Or the timing may be made as accurate as desired by similar methods.

The abovey discussion thus brings out thev purposes o'ffthestepping switch, which are to provideacc'urate,timing Iwhile at the same an'additional -minute period,y

' every 36 seconds.

timecausi-ng'lamp to light only ,at` thetei'-y lmination ofaffa'irly long interval; Thus if i lamp 14 were connected directly to the timing device 15 through 'operation of thestart key 13,'theother apparatus beingassumed for the moment omitted, the lamp would flash On the other hand, if under the same assumptions, the clock mecha- `nism 15 were adjusted to operate once every t 6 minutes, a call would be timed at 6 minutes which was anywhere from Oto 6' minutesin length, depending onho-w soon. key 13 happened to be depressed after the last operation `of mechanism 15.`

`W'hat is claimed is:

trolled `by said relay means to, maintain non-operated saidV stepping switchY in its position while said-relay means is released and to n*permit yth-e operation lay means, means for lconnecting said f stepping switch to said pulse source for operation thereby, and signalingmeans associated with. the nal stepjof said stepping switch opera-.

ble while-said switch is connected thereto.

2.aMeans-,for timing telephone-calls com-v prising in combination, means forproducing electrical pulses periodically, a stepping switch operable one step by'eachf said pulse,

`a telephone circuit,acord circuitl for connec-V tion thereto, relayk means associated with vsaid cord and'adapted to be operated by the connection of saidl cord to said telephonecircuit and to vlie-releasedbythe disconnection.y

thereof, means controlled by said-relaymea1is to maintain said stepping switch in its noni yoperated position While said relay means is. 'released and to permit the operation of said stepping switchy during operation of said re- 1'..,Means.-for timingtelephone calls com-f otsaidstepypingIsWitChduring operation of saidk re` lay means,'means for connecting said stepc ping switch tosaid pulsey source for operation f thereby, signaling Vmeans associated with the Y final-step of saidstepping switch operable while said switch is connected thereto, and means for restoring vsaid stepping switch to its nonoperated position to startanewits f;

operationto light saidsignaling means; t

3.` Ina telephone system consisting of 'subscribei's7V lines and a link. circuit forinterconnectingthe same, means for timing' calls `Yover ksaid Ylines comprising inlv combination,

means'fo'r producing electrical pulses 'periodically, a, stepping switch operable by said pulses, relay means associated-'with said link circuit operablejwhile the link" circuitis connected to a called subscribers line,'meansconerator subsequently illtrolled by said relay means to place the stepping switch in its non-operated position while said relay means is released, switching means controlled by the operator for connecting said ping switch to said pulse source for operation thereby one step for each pulse, signaling means associated with thc final step of said stepping switch and operable while said switch is connected thereto.

L In a telephone system consisting of subscribers lines and a link circuit for interconnecting the same, means for timing calls over said lines comprising in combination, means for producing electrical pulses periodically, a stepping switch operable by said pulses, relay means associated with said link circuit operable while the link circuit is connected to a called subscribers line, means controlled by said relay means to place the stepping switch in its non-operated position while the said relay means is released, switching means controlled by the operator for connecting said stepping switch to said pulse source for operation thereby one step for Ieach pulse, signaling means associated with the filial step of said stepping switch and opeiable while said switch is connected thereto, means controlled by the operator to restore said stepping switch to its non-operated position to start anew its operation by said pulses.

5. In a telephone system consisting of subscribers lines connected to a central oflice and a link circuit thereat for interconnecting said lines, means associated with said link circuit for timing calls over said lines, comprising in combination, means for producing electrical pulses periodically, switching means adapted to be operated from a first to a second position by application of a predetermined number of said pulses thereto, means controlled by said link circuit to maintain said switching means in said first position while said link circuit is disconnected from a called subscribers line, means cont-rolled by the opto such a connection to connect said switching means to said pulse source for operation thereby from Said first to said second position, and signaling means operable while said switching means is operated to said second position.

6. In a telephone system consisting of subscribers lines connected to a central oflice and a link circuit thereat for interconnecting said lines, means associated with said link circuit for timing calls over said lines, comprising in combination, means for producing electrical pulses periodically, switching means adapted to be operated from a first to a second position by application of a predetermined number of said pulses thereto, means controlled by said link circuit to maintain said switching means in said first position while said link circuit is disconnected from a called subscribers line, means controlled by the operator subsequently to such a connection to connect said switchin means to said ulse source for operation t ereby from sai first to said second position, signaling means operable while said switching means is operated to said second position, and means while said link circuit is thus connected to restore said switching means from the second to the first position to start anew its operation to the second position.

7. In a telephone system including subscribers lines and a link circuit for interconnecting the same, means for timing calls over said lines comprisin in combination, means for producing electrlcal pulses periodically, a stepping switch operable step by step by said pulses, relay means adapted to associate said stepping switch with said pulse source for operation thereby, a switch adapted to be closed by the operator for closing a circuit controlled by said stepping switch to operate said relay means, means operable while said link circuit is connected to a called subscribers line for holding said relay means in its operated position, signaling means associated with the final step of said stepping switch and operable thereby while said stepping switch is operated upon said last step, and means controlled by said stepping switch and said relay means and operable when said operator-controlled switch is closed a second time for successively and automatically releasing said relay means, restoring said stepping switch to its non-operated position, opening the circuit of said signaling means and starting anew the operation of said stepping switch.

8. In a telephone system including subscribers lines and a link circuit for interconnecting the same, means for producing electrical pulses periodically, a stepping switch operable step by step by said pulses, relay means adapted to associate said stepping switch with said pulse source for operation thereby, means controlled jointly by the operator and by said stepping switch for o erating said relay means, means operab e while said link circuit `is connected to a called subscribers line for holding said relay means in its operated position, signaling means associated with the final step of said stepping switch and o erable thereby while said stepping switch is operated upon said last step, means controlled jointly by the operator and by said stepping switch for releasing said relay means, and means controlled jointly by said stepping switch and the release of said relay means for restoring said stepping switch to its non-operated position, said means for operating said relay means being also adapted to reoperate said relay means after its release to open the circuit of said signaling means and to start anew the operation of said stepping switch.

9. In a telephone system consisting of subscribers lines and a link circuit for interconnecting the same, means 'for timing calls over sald lines, comprising, 1n comblnation,

switch to said pulse source for operation*y thereby, signaling means associated with the nal step of said stepping switch andoperable thereby while said stepping switch is operated upon said last step, and means for automatically restoring said stepping switch from any oE-normal position to its normal position when said interconnecting link is disconnected from a called subscribers line.

10. In a telephone system including subscribers lines and a link circuit for interconnecting said lines, means for timing calls over said lines, comprising, in combination, means for Vproducing electrical pulses periodically, a stepping switch'operable by said pulses, one step for each pulse, means for normally maintaining said stepping switch non-operated, `means for associating lsaid stepping switch with said pulse source for operation thereby, signaling means associated with the final step of said stepping switch and operable thereby while said stepping switch is operated uponV said last step, means for restoring ysaid stepping switch to its non-operated position, and means for indicating whether said stepping switch has returned to its non-operated position.

In ytestimony whereof, I have signed `my name to this specification this 14th day of August, 1928.

GEORGE n. PETERSON. y 

